This thesis explores the science of solid mechanics via the theory of peridynamics. Peridynamics has several key advantages over the classical theory of elasticity. The most notable of which is the ease with which fractures in the the material are handled. The goal here is to study the two theories and how they relate for problems in which the classical method is known to work well. While it is known that state-based peridynamic models agree with classical elasticity as the horizon radius vanishes, similar results for bond-based models have yet to be developed. In this study, we use numerical simulations to investigate the behavior of bond-based peridynamic models under this limit for a number of cases where analytic solutions of the classical elasticity problem are known. To carry out this study, the integral-based peridynamic model is solved using the finite element method in two dimensions and compared against solutions using the classical approach. / Master of Science

This dissertation presents a new method for obtaining fully anisotropic stiffness tensor for materials containing discontinuous curverd fibers. It is demonstrated that the definition of fiber configuration and configuration averaging allow us to obtain better match with experimental results when compared to theory relying on the assumption of straight fibers. The experimental results are obtained using novel X-ray micro-tomography setup allowing observation of material microstructure under load. / Ph. D.

The objective of this research was to determine if differential camber of prestressed concrete girders could be reduced by accurate prediction of initial camber at release of prestress. Maturity at prestress transfer was used to calculate modulus of elasticity for predicting camber at release. The research consists of a literature review of maturity methods, testing of a standard concrete mix to determine strength and modulus functions and measurement of girder camber and maturity. Both the Nurse-Saul and the Arrhenius maturity models were evaluated. Maturity relationships were developed for concrete mixes containing Type II and Type III cements. A relationship of modulus as a function of maturity was developed. Seven girders were tested. Camber predictions within 0 to ¼ in. of actual camber were obtained using modulus of elasticity calculated from a maturity based function. Comparison was made between maturity based modulus and standard strength based modulus models. Camber predictions based on modulus calculated based on field cured cylinder strengths were within 0 to ½ in. / Master of Science

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published_or_final_version / Civil Engineering / Master / Master of Science in Engineering

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Approved for public release; distribution is unlimited / Determining bulk mechanical properties from microscopic forces has become important in the light of utilizing nano-scale systems. The molecular dynamics model was used to determine the modulus of elasticity and shear modulus of pure metallic micro lattice structures. Preliminary results indicate that the modulii of elasticity is determined to within 15% accuracy for 5 different metals of 500-atom structures when compared to the experiment values of bulk materials. Furthermore the elastic modulus for copper structures was computed with different temperatures, different magnitudes of stresses and various kinds of dislocations. From the preliminary results, it is concluded that the model accurately determines the mechanical properties of the nano-scale systems. / Outstanding Thesis / Canadian Navy author.